This present invention relates to ceramic nanotubes composites, in general augmented polymethylmethacrylate use in medicine or dentistry as a bone cement, dental restoration or other type of medical or dental prosthesis and methods of manufacture or use.
Bone cement is generally composed of a material known as polymethylmethacrylate (PMMA), and has been used by orthopedic surgeons for more than six decades. The first use of bone PMMA cement was in 1958 when British orthopedic surgeon Sir John Charnley implanted a hip endoprosthesis using PMMA. PMMA allows for the implantation and fixation of prostheses to the bone and has been the subject to continuous development in parallel with improvements of surgical techniques.
Bone cement tends to be a compound consisting of 90% PMMA. The remaining material is mainly crystals of barium or zirconium oxide that make the resulting product radio-opaque. The microscopic structure of bone cement consists of two substances glued together. One substance consists of pre-polymerized PMMA, supplied as “pearls.” These “pearls” are supplied as a white powder. The preparation of bone cement involves mixing powdered PMMA (the “pearl” mixture) with a liquid containing monomeric methylmethacrylate (MMA) in the presence of a catalyst. The powder quickly dissolves in the monomer and undergoes a polymerization reaction at room temperature to form putty-like cement. The polymerizing fluid glues together the pearls into a firm, strong, but brittle mass. When the liquid monomer polymerizes and the bone cement hardens, the individual pearls are entrapped and glued within a net of the polymerized monomer. There is no chemical binding, however, between the pearls and the polymerized monomer.
The term cement in this field may be a misnomer. Most often the word cement is used to describe something that adheres, or sticks together, two substances or materials. Cement implies that the material sticks the implant into the bone. Bone cement acts not as a glue but as a filler, like grout. It is added during surgery. The reason is that this material acts as a space-filler. It fills the void between the implant and surrounding bone by creating a tight space for the implant to be held firmly against the bone. Plexiglas® or Lucite® are materials that consist of nearly pure PMMA. Plexiglas® is one of the strongest plastics.
Bone Cements for primary arthroplasty are in widespread use by orthopedists and other surgeons. Bone cement is a substance commonly used for fixation of artificial joints in bone and is extensively used in hip and knee replacement surgery. Various types of bone cements are available to surgeons that vary in regard to viscosity, processing, content, and application properties.
Many surgeons mix prophylactic antibiotics into the bone cement while mixing the components together. Many types of antibiotics can be used in the mixing process, the typical antibiotics used consist of gentamicin, tobramycin or vancomycin. Worldwide tobramycin is very commonly used. Gentamicin and tobramycin are an aminoglycoside antibiotic used to treat various types of bacterial infections, particularly Gram-negative infections. Vancomycin is a glycopeptides antibiotic used in the prophylaxis and treatment of infections caused by Gram-positive bacteria. Surgeons in the United States predominantly use gentamicin. These antibiotics are available in a powdered form that can easily be mixed into the PMMA. Once PMMA is mixed with antibiotics and used in a procedure the antibiotics will leak from the bone cement into the surrounding areas. The local concentration of antibiotics is usually sufficient to initially kill the bacteria left in the operative wound.
However, addition of antibiotics to bone cement leads to a weakening of the cement. It has been demonstrated that addition of antibiotics to bone cement leads to a loss of mechanical strength. There is also limited sustained release of the antibiotics from the PMMA over a longer time period. This limited release could be only 3%-5% of the loaded antibiotics. Mixing the antibiotics in uniformly can be difficult even when done with a sonicator. PMMA is not a porous material. Close to 70 percent of the antibiotics which are released are released within the first 24 hours in standard commercially viable bone cements. This release also only constitutes a low percentage of the total available antibiotic. The non-porous nature of PMMA bone cement causes limited release of the antibiotics that are widely (and unevenly) distributed throughout the cement sample.
What is needed is a bone cement that has been augmented with a biocompatible material that can both add strength to prevent mechanical failure, significantly increase adhesion and also act to provide a sustained release of a substance of interest.
The disclosure allows for a novel bone cement material that can have improved material strength, adhesiveness and delivery properties.